Tachikawa produced a trainer prototype, the R-5,
in 1933 as a private venture. This was a very small aircraft with a 125
hp (93 kW) engine, but it piqued the Army's interest enough that
Tachikawa
was instructed in April 1934 to design a trainer that could be used for
either basic or intermediate training, depending on the engine with
which it was equipped. Though skeptical of the concept, Tachikawa's
design team, led by Endo Ryokichi, designed the Ki-9 to take either a
350 hp (261 kW) engine and full blind instrumentation for intermediate
training or a 150 hp (112 kW) engine and only the most basic
instrumentation for basic training. Three prototypes were ready late
1934 and the first made its maiden flight on 7 January 1935. Handling
and maneuverabily were disappointing and modifications were made to
shift the center of gravity further aft. The third prototype was the
first basic trainer variant and, in its case, the center of gravity was
too far aft. As a result, only the intermediate trainer version was
accepted for production.

The Ki-9 "Spruce" remained the Japanese Army's
main
intermediate trainer aircraft throughout the Second Sino-Japanese War and during the
Pacific War. It was also used
by the Thai and Manchurian air forces, and postwar
by the Indonesian
air force.